A typical refrigeration system has four basis components: a compressor, a condenser, an evaporator, a circulating refrigerant an expansion valve and the necessary plumbing to securely connect the components. These components are essentially the same regardless of the size of the system. The refrigerant, to begin with, is in a gaseous state and compressed in a compressor so as to produce high pressures and temperatures. When the gas temperature/pressure in the compressor is greater than that of the condenser, gas will move from the compressor to the condenser. In the condenser, the refrigerant vapor is liquified and then transported to the expansion valve where the refrigerant runs into a constriction that does not allow it to pass through easily. As a result, the pressure and hence the temperature of the liquid refrigerant coming out of the valve and flowing into the evaporator drops considerably. In the evaporator coil, heat exchange with the warmer environment takes place and the refrigerant boils and changes phase from liquid to vapor. After evaporating into its gaseous form, the gaseous refrigerant is moved to the compressor to repeat the cycle.
In most cases, refrigerant supplied to the evaporator exists in both liquid and vapor form with only a small amount of vapor. To begin with, the refrigerant that enters the the expansion valve from the condenser is generally in 100% liquid form at a high temperature of approximately 105 deg C. (corresponding to a pressure of 278 psig). Once it passes through the expansion valve, the pressure and temperature drop drastically (to about 41 deg F.). The sudden drop in temperature causes the boiling point or saturation temperature of the liquid refrigerant to drop. Hence some of the liquid boils off and flashes into vapor (flash gas). The refrigerant entering the evaporator is therefore partially in liquid form with a smaller vapor fraction. The liquid in the evaporator is in an adiabatic state and therefore cannot absorb or reject heat. Only when liquid changes to the vapor state, the refrigerant can absorb heat from the warmer environment that needs to be cooled.
For efficient heat transfer through the evaporator coil, it would be beneficial to utilize as much of the evaporator coil area as possible. But the inefficient flow rate through the evaporator leads to inefficient cooling and build-up of frost or ice especially in the initial lower portion of the coil, leading to poor heat conduction through the evaporator coil and inefficient cooling.
The present invention overcomes the foregoing problems by providing an apparatus designed to improve the efficiency of a heat exchange system wherein the refrigerant is sufficiently vaporized before entering the evaporator coils so that the refrigeration mixture has higher vapor content than a normal refrigeration system.